CN113765389B

CN113765389B - DC-DC converter

Info

Publication number: CN113765389B
Application number: CN202010492761.9A
Authority: CN
Inventors: 王威; 吴权派
Original assignee: Suzhou Meanwell Technology Co ltd
Current assignee: Suzhou Meanwell Technology Co ltd
Priority date: 2020-06-03
Filing date: 2020-06-03
Publication date: 2024-05-24
Anticipated expiration: 2040-06-03
Also published as: CN113765389A

Abstract

The invention mainly provides a DC-DC converter, which adopts an active clamping forward direction or an active clamping flyback direction, and comprises the following components: a transformer, a first clamping unit, a first MOSFET component, a second clamping unit, a second MOSFET component, a third MOSFET component, a first inductor and a second inductor. Specifically, the present invention utilizes the first clamping unit and the second clamping unit to stably control the drain-source Voltage (VDS) of the first MOSFET device and the second MOSFET device, so that the turn-off stress of the drain-source Voltage (VDS) of each MOSFET device is balanced, thereby avoiding the high voltage spike (high voltage spike) of the specific MOSFET device. Meanwhile, the invention utilizes the first inductor to reduce the reverse recovery negative current of the body diode (body diode) of the third MOSFET component, and simultaneously relieves the ringing phenomenon of the negative current.

Description

DC-DC converter

Technical Field

The present invention relates to a power supply device, and more particularly to a dc-dc converter employing active clamping forward or active clamping flyback to improve the high voltage spike (high voltage spike) phenomenon of a power switch and to suppress reverse recovery negative current of a parasitic diode and ringing thereof.

Background

The switching power supply (Switch Mode Power Supply, SMPS) has been widely used in various electronic products because of its high power factor, high conversion efficiency, small size, and light weight. Depending on the specific driving voltages required for different electronic products and/or electronic components, for example: the voltage output by the switching power supply can further utilize the dc-dc converter to perform step-up or step-down processing to provide proper driving voltage to the electronic product and/or the electronic component. Types of existing dc-dc converters include: buck converters, boost converters, buck/boost converters, full-bridge converters, forward converters, flyback converters, push-pull converters, isolated full-bridge converters, and isolated half-bridge converters.

Fig. 1 shows a circuit topology of a conventional active clamp forward converter, and fig. 2 shows a circuit topology of a conventional alternative active clamp forward converter. Both the circuit topology of fig. 1 and the circuit topology of fig. 2 include: an isolation transformer 10', a first switch Q1', a second switch Q2', a third switch Q3', an energy storage inductor L1', a first capacitor C1', a second capacitor C2', a third capacitor C3', a fourth capacitor C4', a first diode D1', a second diode D2', and a third diode D3'. The second diode D2' and the third diode D3' form an output rectifying unit, and the fourth capacitor C4' is used as an output filtering unit. In more detail, the first switch Q1 'and the second switch Q2' form a main switching unit of the active clamp forward converter, and are connected in parallel.

It should be noted that, in the circuit topology of fig. 1, the second capacitor C2 'and the third capacitor C3' are both clamp capacitors. On the other hand, the third switch Q3' is a clamp switch, which is also connected in parallel with the first switch Q1' and the second switch Q2'. While the active clamp forward converter is operating in a resonant mode, a positive voltage (hv+) charges a clamp capacitance through a body diode (Q31 ') of the third switch Q3'. However, in operation, the reverse recovery time (Reverse recovery time, trr) of the body diode Q31 'of the third switch Q3' causes reverse recovery negative current ringing. Furthermore, the main switch of the active clamp forward converter shown in fig. 1 includes a first switch Q1 'and a second switch Q2' connected in parallel with each other. For practical purposes, the lengths of the copper foil wires of each MOSFET device (i.e., the first switch Q1 'and the second switch Q2') coupled to the positive voltage (hv+) and the negative voltage (HV-) are different, and the values of the line inductances derived from the copper foil wires of different lengths are different, so that the turn-off stress of the drain-source Voltage (VDS) of each MOSFET device is not balanced, and thus the MOSFET device further from the clamp unit is in high voltage spike (high voltage spike). In this case, in order to avoid breakdown of the MOSFET device caused by the high voltage spike (Punch through effect), the MOSFET device with high VDS and low rds_on characteristics must be selected as the component of the main switching unit of the active clamp forward converter. However, this in turn results in increased design and manufacturing costs for the active clamp forward converter shown in FIG. 1.

In the active clamp forward converter shown in fig. 2, the first switch Q1 'and the second switch Q2' are also connected in parallel to each other and form a main switching unit. Unlike the circuit topology of fig. 1, the active clamp forward converter of fig. 2 includes a third switch Q3 'that is Cascode (Cascode) with the first switch Q1', and a second capacitor C2 '(i.e., clamp capacitor) coupled between the drain terminal of the third switch Q3' and the positive voltage (hv+). In the actual operation of the active clamp forward converter shown in fig. 2, the reverse recovery time (Trr) of the body diode Q31 'of the third switch Q3' also causes reverse recovery negative current ringing. On the other hand, the values of the derived line inductances due to the copper foil wires of different lengths will be different for the first switch Q1 'and the second switch Q2' connected in parallel with each other, as will the high voltage spikes (high voltage spike) to which each MOSFET device is subjected. Actual measurement shows that the phase difference between the high voltage protruding tip of the first switch Q1 'and the high voltage protruding tip of the second switch Q2' is 10% -20%.

On the other hand, fig. 3 shows a circuit topology of an active clamp flyback converter according to the prior art, and fig. 4 shows a circuit topology of another active clamp flyback converter according to the prior art. The circuit topology of fig. 3 and the circuit topology of fig. 4 both include: an isolation transformer 10b, a first switch Q1b, a second switch Q2b, a third switch Q3b, an energy storage inductor L1b, a first capacitor C1b, a second capacitor C2b, a third capacitor C3b, a fourth capacitor C4b, a fifth capacitor C4b, a sixth capacitor C6b, a first diode D1b, and a second diode D2b. The second diode D2b and the fourth capacitor C4b form an output rectifying unit, and the fifth capacitor C5b and the sixth capacitor C6b are respectively used as a first output capacitor and a second output capacitor. To explain in more detail, the first switch Q1b and the second switch Q2b constitute a main switching unit of the active clamp flyback converter, and are connected in parallel with each other.

It should be noted that, in the circuit topology of fig. 3, the second capacitor C2b and the third capacitor C3b are both clamp capacitors. On the other hand, the third switch Q3b is a clamp switch, which is also connected in parallel with the first switch Q1b and the second switch Q2b. While the active clamp flyback converter operates in a resonant mode, a positive voltage (hv+) charges a clamp capacitance through a body diode (Q31') of the third switch Q3 b. However, in practical operation, the reverse recovery time (Reverse recovery time, trr) of the body diode Q31b of the third switch Q3b causes reverse recovery negative current ringing. Furthermore, the main switch of the active clamp flyback converter shown in fig. 3 includes a first switch Q1b and a second switch Q2b connected in parallel with each other. For practical purposes, the lengths of the copper foil wires of each MOSFET device (i.e., the first switch Q1b and the second switch Q2 b) coupled to the positive voltage (hv+) and the negative voltage (HV-) are different, and the values of the line inductances derived from the copper foil wires of different lengths are different, so that the turn-off stress of the drain-source Voltage (VDS) of each MOSFET device is not uniform, and thus the MOSFET device further from the clamp unit is in high voltage spike (high voltage spike). In this case, in order to avoid breakdown of the MOSFET device caused by the high voltage spike (Punch through effect), the MOSFET device with high VDS and low rds_on characteristics must be selected as the component of the main switching unit of the active clamp flyback converter. However, this in turn results in increased design and manufacturing costs for the active clamp flyback converter shown in fig. 3.

In the active clamp flyback converter shown in fig. 4, the first switch Q1b and the second switch Q2b are also connected in parallel with each other and constitute a main switching unit. Unlike the circuit topology of fig. 3, the active clamp flyback converter of fig. 4 includes a third switch Q3b that is Cascode (Cascode) with the first switch Q1b, and a second capacitor C2b (i.e., clamp capacitor) is coupled between the drain terminal of the third switch Q3b and the positive voltage (hv+). In the actual operation of the active clamp flyback converter shown in fig. 4, the reverse recovery time (Trr) of the body diode Q31b of the third switch Q3b also causes reverse recovery negative current ringing. On the other hand, the values of the line inductances derived from the copper foil wires of different lengths will be different for the first switch Q1b and the second switch Q2b connected in parallel with each other, and the high voltage spikes (high voltage spike) to which each MOSFET device is subjected will be different. Actual measurement shows that the phase difference between the high voltage protruding tip of the first switch Q1b and the high voltage protruding tip of the second switch Q2b is 10% -20%.

From the above description, there is still room for further improvement in the circuit topology design of the conventional active clamp forward converter and the active clamp flyback converter. In view of the above, the present inventors have studied the invention as much as possible, and have finally developed a dc-dc converter employing an active clamp forward type or an active clamp flyback type.

Disclosure of Invention

The main object of the present invention is to provide a DC-DC converter employing an active clamp forward or an active clamp flyback, which comprises: a transformer, a first clamping unit, a first MOSFET component, a second clamping unit, a second MOSFET component, a third MOSFET component, a first inductor and a second inductor. The invention uses the first clamping unit and the second clamping unit to stably control the drain-source Voltage (VDS) of the first MOSFET component and the second MOSFET component, so that the turn-off stress of the drain-source Voltage (VDS) of each MOSFET component is balanced, thereby avoiding the phenomenon of high voltage spike (high voltage spike) of a specific MOSFET component. Meanwhile, the invention utilizes the first inductor to reduce the reverse recovery negative current of the body diode (body diode) of the third MOSFET component, and simultaneously relieves the ringing phenomenon of the negative current.

To achieve the above object, the present invention provides a first embodiment of the dc-dc converter, which is applied as a dc-dc converter and comprises:

The transformer is provided with a first input end, a second input end, a first output end and a second output end, and the first input end is coupled with a positive voltage;

A first clamping unit having a first end, a second end and a third end, and coupled to the second input end of the transformer by the first end;

A first MOSFET device having a gate terminal, a drain terminal and a source terminal, and coupled to the first terminal of the first clamp by the drain terminal and to the second terminal of the first clamp by the source terminal;

A second clamping unit having a first end, a second end and a third end, wherein the first end is coupled to the second input end of the transformer, and the third end is coupled to the third end of the first clamping unit;

A second MOSFET device having a gate terminal, a drain terminal and a source terminal, and coupled to the first terminal of the second clamp by the drain terminal and to the second terminal of the second clamp by the source terminal; wherein the source terminal of the first MOSFET device and the source terminal of the second MOSFET device are both coupled to a negative voltage (HV-);

A third MOSFET device having a gate terminal, a drain terminal, and a source terminal, and coupled with the source terminal to the second input terminal of the transformer, thereby being connected in parallel with the drain terminal of the first MOSFET device, the first terminal of the first clamp, the drain terminal of the second MOSFET device, and the first terminal of the second clamp;

A first inductor having one end coupled to the drain terminal of the third MOSFET device and the other end coupled to the third terminal of the first clamping unit and the third terminal of the second clamping unit; and

And a second inductor coupled to the first output terminal of the transformer.

In order to achieve the above object, the present invention provides a second embodiment of the dc-dc converter, which comprises:

A first clamping unit having a first end, a second end and a third end, and coupled to the first input end of the transformer by the second end;

a first MOSFET device having a gate terminal, a drain terminal and a source terminal, and coupled to the first terminal of the first clamp unit by the drain terminal and coupled to a negative voltage by the source terminal;

a second clamping unit having a first end, a second end and a third end, wherein the second end is coupled to the first input end of the transformer, and the third end is coupled to the third end of the first clamping unit;

a second MOSFET device having a gate terminal, a drain terminal and a source terminal, and coupled to the first terminal of the second clamp by the drain terminal and coupled to the negative voltage by the source terminal;

And a second inductor coupled to the first output terminal of the transformer.

In order to achieve the above object, the present invention provides a third embodiment of the dc-dc converter, which is applied as a dc-dc converter and includes:

A first inductor having one end coupled to the drain terminal of the third MOSFET device and the other end coupled to the third terminal of the first clamping unit and the third terminal of the second clamping unit;

A first output capacitor having a first end and a second end, and connected in parallel with the first output end and the second output end of the transformer by the first end and the second end; and

The second inductor is provided with a first end and a second end, and the first end of the second inductor is coupled with the first end of the first output capacitor.

Further, to achieve the above object, the present invention provides a fourth embodiment of the dc-dc converter, which includes:

Drawings

FIG. 1 is a circuit topology diagram of an active clamp forward converter according to the prior art;

FIG. 2 is a circuit topology diagram of another prior art active clamp forward converter;

FIG. 3 is a circuit topology of an active clamp flyback converter according to the prior art;

FIG. 4 is a circuit topology of another prior art active clamp flyback converter;

FIG. 5 shows a circuit topology of a first embodiment of a DC-DC converter according to the present invention;

FIG. 6 shows a circuit topology of a second embodiment of the DC-DC converter of the present invention;

FIG. 7 is a circuit topology of a third embodiment of a DC-DC converter according to the present invention; and

Fig. 8 shows a circuit topology of a fourth embodiment of the dc-dc converter of the present invention. The main symbols in the drawings illustrate:

1. DC-DC converter

10. Transformer

11. First clamping unit

12. Second clamping unit

13. Output rectifying unit

14. Output filter unit

C1 First capacitor

C2 Second capacitor

C3 Third capacitor

C4 Fourth capacitor

D1 First diode

D2 Second diode

D3 Third diode

D4 Fourth diode

L1 first inductor

L2 second inductor

Q1 first MOSFET component

Q2 second MOSFET component

Q3 third MOSFET component

10A transformer

11A first clamping unit

12A second clamping unit

13A lead-out rectifying unit

C1a first capacitor

C2a second capacitor

C3a third capacitor

C4a fourth capacitor

Co1a first output capacitor

Co2a second output capacitor

D1a first diode

D2a second diode

D3a third diode

L1a first inductor

L2a second inductor

Q1a first MOSFET component

Q2a second MOSFET component

Q3a third MOSFET component

10' Isolation transformer

C1' first capacitor

C2' second capacitor

C3' third capacitor

C4' fourth capacitor

D1' first diode

D2' second diode

D3' third diode

L1' energy storage inductor

Q1' first switch

Q2' second switch

Q3' third switch

Q31' body diode

10B isolation transformer

C1b first capacitor

C2b second capacitor

C3b third capacitor

C4b fourth capacitor

C5b fifth capacitor

C6b sixth capacitor

D1b first diode

D2b second diode

L1b energy storage inductor

Q1b first switch

Q2b second switch

Q3b third switch

Q31b body diode

Detailed Description

In order to more clearly describe a dc-dc converter employing an active clamp forward or an active clamp flyback according to the present invention, the following description will be made with reference to the accompanying drawings.

The invention provides a DC-DC converter, which is applied as an active clamping forward power converter or an active clamping flyback power converter, and is integrated in a power supply device, a power conversion device or an LED driving power device.

First embodiment

Fig. 5 shows a circuit topology of a first embodiment of a dc-dc converter according to the invention. As shown in fig. 5, a first embodiment of the dc-dc converter 1 of the present invention adopts an active clamp forward mode, and mainly includes: a transformer 10, a first clamping unit 11, a first MOSFET device Q1, a second clamping unit 12, a second MOSFET device Q2, a third MOSFET device Q3, a first inductor L1, and a second inductor L2. In the first embodiment, the transformer 10 has a first input terminal, a second input terminal, a first output terminal, and a second output terminal. The first clamping unit 11 has a first end, a second end and a third end, and is coupled to the second input end of the transformer 10 by the first end. More specifically, the first clamping unit 11 includes a first diode D1 and a first capacitor C1.

As shown in fig. 5, an anode terminal of the first diode D1 serves as the first terminal of the first clamping unit 11. The first capacitor C1 has a first end and a second end; the first end of the first capacitor C1 is coupled to a cathode end of the first diode D1 to serve as the third end of the first clamping unit 11, and the second end of the first capacitor C1 serves as the second end of the first clamping unit 11. In the first embodiment, the first MOSFET device Q1 has a gate terminal, a drain terminal and a source terminal, and is coupled to the first terminal of the first clamp 11 by the drain terminal and is coupled to the second terminal of the first clamp 11 by the source terminal.

On the other hand, the second clamping unit 12 has a first end, a second end and a third end, and is coupled to the second input end of the transformer 10 by the first end and is coupled to the third end of the first clamping unit 11 by the third end. More specifically, as shown in fig. 5, the second clamping unit 12 includes a second diode D2 and a second capacitor C2, wherein an anode terminal of the second diode D2 is used as the first terminal of the second clamping unit 12. The second capacitor C2 has a first end and a second end. As shown in fig. 5, the first end of the second capacitor C2 is coupled to a cathode end of the second diode D2 to serve as the third end of the second clamping unit 12, and the second end of the second capacitor C2 serves as the second end of the second clamping unit 12.

FIG. 5 also shows that the second MOSFET device Q2 has a gate terminal, a drain terminal and a source terminal, and is coupled to the first terminal of the second clamp 12 by the drain terminal and is coupled to the second terminal of the second clamp 12 by the source terminal. As can be seen from fig. 5, the source terminal of the first MOSFET device Q1 and the source terminal of the second MOSFET device Q2 are both coupled to the negative voltage (HV-). On the other hand, the third MOSFET device Q3 has a gate terminal, a drain terminal and a source terminal, and is coupled with the source terminal thereof to the second input terminal of the transformer 10, thereby being connected in parallel with the drain terminal of the first MOSFET device Q1, the first terminal of the first clamping unit 11, the drain terminal of the second MOSFET device Q2, and the first terminal of the second clamping unit 12. It should be noted that, in the first embodiment, the first inductor L1 is coupled to the drain terminal of the third MOSFET device Q3 at one end thereof, and is coupled to the third terminal of the first clamping unit 11 and the third terminal of the second clamping unit 12 at the other end thereof.

In addition, fig. 5 further illustrates that the dc-dc converter 1 of the present invention further includes: an output rectifying unit 13, an output filtering unit 14, a second inductor L2, and a third capacitor C3. One end of the third capacitor C3 is coupled to the first input terminal of the transformer 10 and the positive voltage (hv+), and the other end is coupled to the negative voltage (HV-). On the other hand, the second inductor L2 is coupled to the first output terminal of the transformer 10, and the output rectifying unit 13 is coupled to the first output terminal and the second output terminal of the transformer 10, such that the second inductor L2 is coupled to the first output terminal of the transformer 10 through the output rectifying unit 13. And, the output filter unit 14 is coupled to the second inductor L2. Furthermore, the output rectifying unit 13 is coupled to the two output terminals of the transformer 10, and includes a third diode D3 and a fourth diode D4. The output filter unit 14 includes a fourth capacitor C4 and is coupled to the output rectifying unit 13.

Experimental example

The following table (1) collates some experimental data, including: drain-source Voltage (VDS), reverse recovery negative current, and negative current ringing.

Watch (1)

Further, in the case of the prior art active clamp forward converter (shown in fig. 1), the drain-source Voltage (VDS) is measured from the first switch Q1', and the reverse recovery negative current and negative current ringing is measured from the third switch Q3'. In the case of the present invention employing an actively clamped forward DC-DC converter 1 (shown in FIG. 5), the drain-to-source Voltage (VDS) is measured from the first MOSFET device Q1, while the reverse recovery negative current and negative current ringing is measured from the third MOSFET device Q3. From the experimental data in table (1), it is easy to understand that the dc-dc converter 1 of the present invention can improve the high voltage spike (high voltage spike) phenomenon of the power switch and suppress the reverse recovery negative current of the parasitic diode and its ringing.

Second embodiment

Fig. 6 shows a circuit topology of a second embodiment of the dc-dc converter of the present invention. As can be seen from comparing fig. 6 and fig. 5, the second embodiment of the dc-dc converter 1 of the present invention adopts an active clamping forward mode, and it also mainly includes: a transformer 10, a first clamping unit 11, a first MOSFET device Q1, a second clamping unit 12, a second MOSFET device Q2, a third MOSFET device Q3, a first inductor L1, and a second inductor L2. Unlike the circuit topology of the first embodiment, the third MOSFET device Q3 is stacked (Cascode) with the first MOSFET device Q1, rather than being connected in parallel, in the layout of the circuit topology of the second embodiment.

In more detail, in the second embodiment, the transformer 10 has a first input terminal, a second input terminal, a first output terminal, and a second output terminal, and is coupled to a positive voltage (hv+) at the first input terminal. The first clamping unit 11 also has a first end, a second end and a third end, and is coupled to the first input end of the transformer 10 by the second end. As shown in fig. 6, the first clamping unit 11 includes a first diode D1 and a first capacitor C1. Wherein an anode terminal of the first diode D1 is used as the first terminal of the first clamping unit 11, and the first capacitor C1 has a first terminal and a second terminal. The first end of the first capacitor C1 is coupled to a cathode end of the first diode D1 to serve as the third end of the first clamping unit 11, and the second end of the first capacitor C1 serves as the second end of the first clamping unit 11.

In the second embodiment, the first MOSFET device Q1 has a gate terminal, a drain terminal and a source terminal, and is coupled to the first terminal of the first clamp 11 by the drain terminal thereof and is coupled to a negative voltage (HV-) by the source terminal thereof. On the other hand, the second clamping unit 12 has a first end, a second end and a third end, and is coupled to the first input end of the transformer 10 by the second end and is coupled to the third end of the first clamping unit 11 by the third end. More specifically, the second clamping unit 12 includes a second diode D2 and a second capacitor C2, wherein an anode terminal of the second diode D2 is used as the first terminal of the second clamping unit 12. As shown in fig. 6, the second capacitor C2 has a first end and a second end, and the first end of the second capacitor C2 is coupled to a cathode end of the second diode D2 so as to serve as the third end of the second clamping unit 12, and the second end of the second capacitor C2 serves as the second end of the second clamping unit 12.

FIG. 6 also shows that the second MOSFET device Q2 has a gate terminal, a drain terminal and a source terminal, and is coupled to the first terminal of the second clamp 12 at its drain terminal and is coupled to the negative voltage (HV-) at its source terminal. In the second embodiment, the third MOSFET device Q3 has a gate terminal, a drain terminal and a source terminal, and is coupled to the second input terminal of the transformer 10 by the source terminal thereof, thereby being connected in parallel with the drain terminal of the first MOSFET device Q1, the first terminal of the first clamping unit 11, the drain terminal of the second MOSFET device Q2, and the first terminal of the second clamping unit 12. It should be noted that, in the second embodiment, the first inductor L1 is coupled to the drain terminal of the third MOSFET device Q3 at one end thereof, and is coupled to the third terminal of the first clamping unit 11 and the third terminal of the second clamping unit 12 at the other end thereof.

In addition, fig. 6 also shows that the second embodiment of the dc-dc converter 1 of the present invention further includes: an output rectifying unit 13, an output filtering unit 14, a second inductor L2, and a third capacitor C3. One end of the third capacitor C3 is coupled to the first input terminal of the transformer 10 and the positive voltage (hv+), and the other end is coupled to the negative voltage (HV-). On the other hand, the second inductor L2 is coupled to the first output terminal of the transformer 10, and the output rectifying unit 13 is coupled to the first output terminal and the second output terminal of the transformer 10, such that the second inductor L2 is coupled to the first output terminal of the transformer 10 through the output rectifying unit 13. And, the output filter unit 14 is coupled to the second inductor L2. Furthermore, the output rectifying unit 13 is coupled to the two output terminals of the transformer 10, and includes a third diode D3 and a fourth diode D4. The output filter unit 14 includes a fourth capacitor C4 and is coupled to the output rectifying unit 13.

Third embodiment

Fig. 7 shows a circuit topology of a third embodiment of a dc-dc converter according to the present invention. In the third embodiment, the dc-dc converter 1 employing the active clamp flyback according to the present invention mainly includes: a transformer 10a, a first clamping unit 11a, a first MOSFET device Q1a, a second clamping unit 12a, a second MOSFET device Q2a, a third MOSFET device Q3a, a first inductor L1a, a first output capacitor Co1a, and a second inductor L2a. In the third embodiment, the transformer 10a has a first input terminal, a second input terminal, a first output terminal, and a second output terminal. The first clamping unit 11a has a first end, a second end and a third end, and is coupled to the second input end of the transformer 10a by the first end. More specifically, the first clamping unit 11a includes a first diode D1a and a first capacitor C1a.

As shown in fig. 7, an anode terminal of the first diode D1a serves as the first terminal of the first clamping unit 11 a. The first capacitor C1a has a first end and a second end; the first end of the first capacitor C1a is coupled to a cathode end of the first diode D1a to serve as the third end of the first clamping unit 11a, and the second end of the first capacitor C1a serves as the second end of the first clamping unit 11 a. In the third embodiment, the first MOSFET device Q1a has a gate terminal, a drain terminal and a source terminal, and is coupled to the first terminal of the first clamping unit 11a by the drain terminal and is coupled to the second terminal of the first clamping unit 11a by the source terminal.

On the other hand, the second clamping unit 12a has a first end, a second end and a third end, and is coupled to the second input end of the transformer 10a by the first end and is coupled to the third end of the first clamping unit 11a by the third end. In more detail, as shown in fig. 7, the second clamping unit 12a includes a second diode D2a and a second capacitor C2a, wherein an anode terminal of the second diode D2a is used as the first terminal of the second clamping unit 12 a. The second capacitor C2a has a first end and a second end. As shown in fig. 7, the first end of the second capacitor C2a is coupled to a cathode end of the second diode D2a so as to serve as the third end of the second clamping unit 12a, and the second end of the second capacitor C2a serves as the second end of the second clamping unit 12 a.

FIG. 7 also shows that the second MOSFET device Q2a has a gate terminal, a drain terminal and a source terminal, and is coupled to the first terminal of the second clamp 12a by the drain terminal and is coupled to the second terminal of the second clamp 12a by the source terminal. As can be seen from fig. 7, the source terminal of the first MOSFET device Q1a and the source terminal of the second MOSFET device Q2a are both coupled to the negative voltage (HV-). On the other hand, the third MOSFET device Q3a has a gate terminal, a drain terminal and a source terminal, and is coupled to the second input terminal of the transformer 10a by the source terminal thereof, thereby being connected in parallel with the drain terminal of the first MOSFET device Q1a, the first terminal of the first clamping unit 11a, the drain terminal of the second MOSFET device Q2a, and the first terminal of the second clamping unit 12 a. It should be noted that, in the third embodiment, the first inductor L1a is coupled to the drain terminal of the third MOSFET device Q3a at one end thereof, and is coupled to the third terminal of the first clamping unit 11a and the third terminal of the second clamping unit 12a at the other end thereof.

In addition, fig. 7 further illustrates that the third embodiment of the dc-dc converter 1 of the present invention further includes: an output rectifying unit 13a, a first output capacitor Co1a, a second inductor L2a, a second output capacitor Co2a, and a third capacitor C3a. One end of the third capacitor C3a is coupled to the first input terminal of the transformer 10a and the positive voltage (hv+), and the other end is coupled to the negative voltage (hv+). On the other hand, the first output capacitor Co1a has a first end and a second end, and is connected in parallel with the first output end and the second output end of the transformer 10a through the first end and the second end. As shown in fig. 7, the output rectifying unit 13a includes a third diode D3a and a fourth capacitor C4a, and is coupled to the first output terminal and the second output terminal of the transformer 10a, such that the first output capacitor Co1a is connected in parallel with the first output terminal and the second output terminal of the transformer 10a through the output rectifying unit 13 a. The second output capacitor Coa2 has a first end and a second end, and is coupled to the second end of the second inductor L2a by the first end.

Further, the present invention utilizes the first clamping unit 11a and the second clamping unit 12a to stably control the drain-source Voltage (VDS) of the first MOSFET device Q1a and the second MOSFET device Q2a, so that the turn-off stress of the drain-source Voltage (VDS) of each MOSFET device is balanced, thereby avoiding the high voltage spike (high voltage spike) of a specific MOSFET device. Meanwhile, the invention also utilizes the first inductor L1a to reduce the reverse recovery negative current of the body diode (body diode) of the third MOSFET component Q3a, and simultaneously relieves the ringing phenomenon of the negative current.

Fourth embodiment

Fig. 8 shows a circuit topology of a fourth embodiment of the dc-dc converter of the present invention. As with the foregoing third embodiment, the fourth embodiment of the dc-dc converter 1 of the present invention also mainly includes: a transformer 10a, a first clamping unit 11a, a first MOSFET device Q1a, a second clamping unit 12a, a second MOSFET device Q2a, a third MOSFET device Q3a, and a first inductor L1a, and a first output capacitor Co1a, and a second inductor L2a. However, unlike the circuit topology of the third embodiment described above, in the layout of the circuit topology of the fourth embodiment, the third MOSFET device Q3a is stacked (Cascode) with the first MOSFET device Q1a, rather than being connected in parallel.

In more detail, in the fourth embodiment, the transformer 10a has a first input terminal, a second input terminal, a first output terminal, and a second output terminal, and is coupled to a positive voltage (hv+) at the first input terminal. The first clamping unit 11a also has a first end, a second end and a third end, and is coupled to the second input end of the transformer 10a by the first end. As shown in fig. 8, the first clamping unit 11a includes a first diode D1a and a first capacitor C1a. Wherein an anode terminal of the first diode D1a is used as the first terminal of the first clamping unit 11a, and the first capacitor C1a has a first terminal and a second terminal. The first end of the first capacitor C1a is coupled to a cathode end of the first diode D1a to serve as the third end of the first clamping unit 11a, and the second end of the first capacitor C1a serves as the second end of the first clamping unit 11 a.

In the fourth embodiment, the first MOSFET device Q1a has a gate terminal, a drain terminal and a source terminal, and is coupled to the first terminal of the first clamp 11a by the drain terminal thereof and is coupled to a negative voltage (HV-) by the source terminal thereof. On the other hand, the second clamping unit 12a has a first end, a second end and a third end, and is coupled to the second input end of the transformer 10a by the first end and is coupled to the third end of the first clamping unit 11a by the third end. More specifically, the second clamping unit 12a includes a second diode D2a and a second capacitor C2a, wherein an anode terminal of the second diode D2a is used as the first terminal of the second clamping unit 12 a. As shown in fig. 8, the second capacitor C2a has a first end and a second end. The first end of the second capacitor C2a is coupled to a cathode end of the second diode D2a to serve as the third end of the second clamping unit 12a, and the second end of the second capacitor C2a serves as the second end of the second clamping unit 12 a.

FIG. 8 also shows that the second MOSFET device Q2a has a gate terminal, a drain terminal and a source terminal, and is coupled to the first terminal of the second clamp 12a at its drain terminal and is coupled to the negative voltage (HV-) at its source terminal. In the fourth embodiment, the third MOSFET device Q3a has a gate terminal, a drain terminal and a source terminal, and is coupled to the second input terminal of the transformer 10a with the source terminal thereof, thereby being connected in parallel with the drain terminal of the first MOSFET device Q1a, the first terminal of the first clamping unit 11a, the drain terminal of the second MOSFET device Q2a, and the first terminal of the second clamping unit 12 a. It should be noted that, in the fourth embodiment, the first inductor L1a is coupled to the drain terminal of the third MOSFET device Q3a at one end thereof, and is coupled to the third terminal of the first clamping unit 11a and the third terminal of the second clamping unit 12a at the other end thereof.

Further, fig. 8 also shows that the fourth embodiment of the dc-dc converter 1 of the present invention further comprises: an output rectifying unit 13a, a first output capacitor Co1a, a second inductor L2a, a first output capacitor Co2a, and a third capacitor C3a. One end of the third capacitor C3a is coupled to the first input terminal of the transformer 10a and the positive voltage (hv+), and the other end is coupled to the negative voltage (hv+). On the other hand, the first output capacitor Co1a has a first end and a second end, and is connected in parallel with the first output end and the second output end of the transformer 10a through the first end and the second end. As shown in fig. 8, the output rectifying unit 13a includes a third diode D3a and a fourth capacitor C4a, and is coupled to the first output terminal and the second output terminal of the transformer 10a, such that the first output capacitor Co1a is connected in parallel with the first output terminal and the second output terminal of the transformer 10a through the output rectifying unit 13 a. The second output capacitor Co2a has a first end and a second end, and is coupled to the second end of the second inductor L2a by the first end.

Thus, the foregoing has outlined rather fully and clearly the basic structure and features of the present invention disclosed herein that employ an active clamp forward or active clamp flyback DC-DC converter. It should be emphasized that the above detailed description is directed to a specific description of a practical embodiment of the invention, but is not intended to limit the scope of the invention, which is defined by the appended claims without departing from the spirit and scope of the invention.

Claims

1. A dc-dc converter comprising:

A first clamping unit having a first end, a second end and a third end, and coupled to the second input end of the transformer by the first end; wherein the first clamping unit includes:

A first diode having an anode terminal as the first terminal of the first clamping unit; and

A first capacitor having a first end and a second end; the first end of the first capacitor is coupled to a cathode end of the first diode so as to serve as the third end of the first clamping unit, and the second end of the first capacitor serves as the second end of the first clamping unit;

A second clamping unit having a first end, a second end and a third end, wherein the first end is coupled to the second input end of the transformer, and the third end is coupled to the third end of the first clamping unit; wherein the second clamping unit includes:

a second diode having an anode terminal as the first terminal of the second clamping unit; and

A second capacitor having a first end and a second end; wherein the first end of the second capacitor is coupled to a cathode end of the second diode to serve as the third end of the second clamping unit, and the second end of the second capacitor serves as the second end of the second clamping unit;

A second MOSFET device having a gate terminal, a drain terminal and a source terminal, and coupled to the first terminal of the second clamp by the drain terminal and to the second terminal of the second clamp by the source terminal; wherein the source terminal of the first MOSFET device and the source terminal of the second MOSFET device are both coupled to a negative voltage;

And a second inductor coupled to the first output terminal of the transformer.

2. The dc-dc converter of claim 1, which is included in a power supply device, a power conversion device, or an LED driving power device.

3. The dc-dc converter of claim 1, further comprising:

the output rectifying unit is coupled with the first output end and the second output end of the transformer, so that the second inductor is coupled with the first output end of the transformer through the output rectifying unit;

An output filter unit coupled to the second inductor; and

One end of the third capacitor is coupled with the first input end of the transformer and the positive voltage at the same time, and the other end of the third capacitor is coupled with the negative voltage.

4. A dc-dc converter comprising:

a first clamping unit having a first end, a second end and a third end, and coupled to the first input end of the transformer by the second end; wherein the first clamping unit includes:

A second clamping unit having a first end, a second end and a third end, wherein the second end is coupled to the first input end of the transformer, and the third end is coupled to the third end of the first clamping unit; wherein the second clamping unit includes:

And a second inductor coupled to the first output terminal of the transformer.

5. The dc-dc converter of claim 4, wherein the dc-dc converter is included in a power supply device, a power conversion device, or an LED driving power device.

6. The dc-dc converter of claim 4, further comprising:

An output filter unit coupled to the second inductor; and

7. A dc-dc converter comprising:

8. The dc-dc converter of claim 7, which is included in a power supply device, a power conversion device, or an LED driving power device.

9. The dc-dc converter of claim 7, further comprising:

The output rectifying unit is coupled with the first output end and the second output end of the transformer, so that the first output capacitor is connected with the first output end and the second output end of the transformer in parallel through the output rectifying unit;

a second output capacitor having a first end and a second end, and coupled to the second end of the second inductor by the first end; and

10. A dc-dc converter comprising:

11. The dc-dc converter of claim 10, wherein the dc-dc converter is included in a power supply device, a power conversion device, or an LED driving power device.